Let's formulate the equations and solve for \( x \), where \( x \) represents the number of days.
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The amount of vanilla ice cream left after \( x \) days can be represented as: \[ 180 - 20x \] This accounts for the initial capacity of 180 cups, minus 20 cups sold per day.
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The amount of chocolate ice cream left after \( x \) days can be represented as: \[ 140 - 16x \] This accounts for the initial capacity of 140 cups, minus 16 cups sold per day.
We want to find the day \( x \) when the amounts of ice cream left in both machines are equal: \[ 180 - 20x = 140 - 16x \]
Now, let's solve this equation step by step:
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Start by moving all terms involving \( x \) to one side and constant terms to the other side: \[ 180 - 140 = 20x - 16x \] \[ 40 = 4x \]
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Divide both sides by 4: \[ x = 10 \]
Thus, the correct response is: \[ 180 - 20x = 140 - 16x; \quad x = 10 \]
This corresponds to the second response option.
In summary: 180 − 20x = 140 − 16x; x = 10